Electrical sostenuto piano



S. COOPER ELECTRICAL SOSTENUTO PIANO Original Filed Dec. 5, 1918 C Inventor;

Patented Aug. 31, 1926.

PATENT OFFICE.

SIMON COOPER, OF BROOKLYN, NEW YORK.

ELECTRICAL SOSTENUTO PIANO.

Application filed December 8, 1918, Serial No. 265,083. Renewed November 19, 1925.

'My present invention relates to what are known as electr'wal sostenuto pianos.

One of the rmcipal objects of the inven. tion is to sync ronize the impulses of an actuating electromagnet with the natural vibrations of the sonorous body which it actuates, which latter, by way of illustration, ma' be a piano string.

nother object of the invention is to provide a simple and inexpensive arrangement of circuit controller for the electromagnet, capable of being readily aQu'sted to secure synchronization between the electrical impulses of the ma rbnen'ts of the string or other vibratorymem- I have accomplished the foregoing and other objects in my invention, by cont-rol- I ling the actuating electromagnet from circuit contacts under control of the stringor other vibrated member and by relatively adjusting said contacts angularly one about the other to a point where the propelling impulses set up in the magnet are in time with the natural vibrations of the vibratory memer. Other features of the invention will apgear as the specification proceeds, attention 'eing now invited to the accompanying drawing forming a part. hereof and wherein I have disclosed the invention embodied in a concrete practical form.

In this drawing, Figure 1 is a partly sectional and more or less diagrammatic view of a form of the invention as adapted to a sostenuto piano, Figure 2 is a sectional view taken on line 2-2 Figure 1, and Figure 3 is a modified form showing the. parts in a slightly adjusted position.

In F in this case is the piano string, is designated 5', the magnet for vibrating the string 1s designated 10. and the magnet-controlling piano key is indicated at 7. This key, when depressed, closes a switch 8, which completes an electric circuit through the electromagnet,

said circuit including a battery or other source of current 9 and being underthe control of a circuit controller which is con- 00 trolled by the vibrating string.

f This circuit controller is of novel construction, embodying an outstanding contact 18. carried by the string, having a down-turned angularly-directed end terminal portion 19, and a relatively stationary cooperating contact- 16 having a terminal offset arm desiget with the vibrating moveigure 1 the vibratory member, which noted 16, said contact 16 being mounted on a support 20, which latter may simply be a part of the piano frame. The stationary arm 16' may have an angular sliding or sweeping engagement with the string-carried contact, as will be clear from Figure 2.

These contacts are relatively adjustable angularly, one about the other, for the purable. for instance, by making them of bendable material. Also, said contacts, one or both of them, may be made relatively resilient and they are of course made of such light material and with such a light contact as not to interfere with the free vibration of the string.

In practice the extension 18 with its "terminal 19 is usually fixed to the string at a point close to one of the supporting bridges and its lateral movement is therefore relatively slight and the impact of terminal 19' with the contact arm 16 is correspondingly slight.

These cooperating contacts are adjusted to energize the magnet at such times only as to produce propelling impulses which will be in time with the natural or free vibrations of the string, or in other words so that the magnet will attract the string only at such times as the string is moving toward the magnet in the course of its own natural vibrations.

There may be objections to making the contact member 16 or equivalent fixed or rigid and accordingly I have specified above that I may make it resilient. Therefore, because of the extremely minute movements of the string in its vibration and of the contact member as it is reacted upon by the string, it would be practically impossible to deter.- mino-the initial relation of the contact arm 16' to the string otherwise than empirically. as is indicated in Figures 2 and 3, this initial position might be anywhere about the cross section of the string. By reason of the fact that the contactarm 16' makes contact with the string terminal 19 at a certain point in the swing of the string, such contact is tangential, as shown in both Figures 2 and 3,

" section of the and it is a very simple matter to adjust the contact, arm 16' angularly about the cross string or terminal until the proper position is found which, upon closing of the circuit by the key 7, results in the production and sustaining of the character istic tone of the string without any undesirable partials or overtones. When this position is found it is fixed, and it is obvious that it will be different for different strings. The result of such adjustment is to bring about an operative accord between the electrical impulses of the magnet and the vibration phase of the particular string.

I claim 1. The method of electromagnetically vibrating a musical strin which comprises controlling the circuit 0% the string-vibrating electromagnet through the medium of a circuit contact carried by the string and a second contact engaged thereby and varying the point of engagement of said contacts angularly about said string until the impulses of the magnet are in synchronism with the natural musical vibrations of the string.

2. The method of electromagnetically vibrating a musical string which comprises controlling the string-vibrating electromagnet through the medium of circuit contacts controlled by the vibration of the string and adjusting the point of engagement of said contacts angularly in respect to the vibratory movement of the string to a point where the string-vibrating impulses of the electromagnet will be in synchronism with the natural musical vibrations of the string.

3. The method of electromagnetically vibrating a musical string which comprises controlling the string-vibrating electromagnet through the medium of circuit contacts controlled by the vibration of the string and empirically fixing the point of engagement of said contacts at a point angularly related to the vibratory movement of the string, Where the impulses of the magnet will be in synchronism with the natural musical vibrations of the string.

4. The method of electromagnetically vibrating a musical string which comprises controlling the energizing circuit of the string-vibrating electromagnet through the medium of a contact outstanding from and carried by the string and a cooperating relatively stationary adjustable contact and adusting said latter contact angularly about the vibrating string-supported contact to bring the impulses of the magnet into synchronism with the natural musical vibrations of thestring.

5. The method of electromagnetically vibrating a muscal string which comprises controlling the energizing circuit of the string-vibrating electromagnet through the medium of a'contactjcarried by the strin having an angularly extending terminal. en

and a relatively stationary adjustable contact engaging said an ular terminal and positioning said adjusta 1e contact angularly about the terminal to bring the impulses of the magnet into synchronism with the natural musical vibrations of the string.

6. The method of electromagnetically vibrating a musical string which consists in controlling an electromagnet for vibrating the string by means of a contact carried by the string and a cooperating relative stationary contact and varying the position of said contacts angularly one about the other until the energization of said magnet is accomplished at such times asto produce propelling impulses by the magnet on the string in the direction in whichthe string is moving in the course of its natural musical vibrations.

7. In a device of the character described, a vibratory string, an electromagnet for vibrating the same and a controlling circuit for said electroma net comprising acontact carried by the vi ratory string and a cooperating contact adjustable around said first contact.

8. In a device of the character described, a vibratory string, an electromagnet for vibrating the same and a controlling circuit for said electromagnet comprising a contact carried by the vibratin string and a 00- operating relatively stationary contact, said contacts being relatively adjustable rotatably one about the other for varying the point of engagement therebetween.

9. In combination with a musical string and an electromagnet for vibrating the same, a controlling circuit for said magnet comprising a contact outstanding from the strin having an angularly extending termina engageable by said angular terminal and relatively adjustable thereabout to vary the point of engagement.

10. In combination with a musical string and an electromagnet for vibrating the same, a controlling circuit for said magnet including a string-carried contact and a resilient contact angularly adjustable about said string-carried contact.

11. In combination with a musical string and an electromagnet for vibrating the same, a controlling circuit for said magnet including cooperating resilient contacts, one of said contacts being carried by the string and said contacts being relatively adjustable angularl one about the other.

In com ination with a musical string and an electromagnet for vibrating the same, a controlling circuit for said magnet including cooperatin resilient contacts, said contacts being re atively adjustable angularly one about the other.

7 13. In combination with a musical string and an electromagnet for Vibrating the same, a controlling circuit for said magnet includin cooperative resilient contacts controlled y the vibratory movement of the strin and said contacts being relatively adjusta 1e angularly one about the other. i

14. The method of electromagnetically vibratin a musical string which comprises contro ling the strin -vibrating electromagnet through the med ium of circuit contacts controlled by the vibrations of the string and adjusting the point of engagement of said contacts angularl in respect of one to the other to a point w ere the string-vibrating impulses of the electromagnet will be in synchronism with the natural musical vibrations of the string.

" 15. The method of electromafinetically viby the string and a cooperating relatively stationary contact and varying the position of said contacts angularly one about the other untilthe energization of said mag net is accomplished at such times as to produce propelling impulses by the magnet on the string in the direction in which the string is moving in the course of its natural musical vibrations.

In testimony whereof I aflix my signature.

SIMON COOPER. 

